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Year 9 · Key Stage 3 · free KS3 maths worksheet

Angles

13 original questions, 49 marks. Type your answers below for an instant mark and a score (algebra in any equivalent form, e.g. 2sqrt(3) or 2√3), or print the worksheet, mark it with the answers sheet, and use the solutions to see every step written out by hand.

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The questions

1

The diagram shows five quadrilaterals, labelled A, B, C, D and E, drawn on a centimetre grid.

  1. Write down the letters of the pair of congruent quadrilaterals.
  2. Write down the mathematical name of quadrilateral A.
ABCDE
2 marks
Show answer
a) A and C b) parallelogram
2

Here is some information about four pairs of triangles.

For each pair, write down the condition (SSS, SAS, ASA or RHS) that shows the triangles are congruent, or write "not necessarily congruent".

  1. Both triangles have two sides of 5 cm and 7 cm, with an angle of 50° between them.
  2. Both triangles have angles of 40°, 60° and 80°.
  3. Both triangles have a right angle, a hypotenuse of 13 cm and another side of 5 cm.
  4. Both triangles have a side of 6 cm with angles of 35° and 70° at each end of it.
4 marks
Show answer
a) SAS b) not necessarily congruent c) RHS d) ASA
3

PQRS is a parallelogram.

Angle P = (3x + 15)° and angle Q = (2x − 10)°. Angles P and Q are next to each other on the same side of the parallelogram.

Work out the value of x. Give a reason for each stage of your working.

PQRS(3x + 15)°(2x − 10)°Diagram NOT accurately drawn
3 marks
Show answer
x = 35
4

AB and CD are parallel lines. The line PQ crosses them at P and Q.

One of the angles at P is 62°, as shown.

  1. Write down the value of x. Give a reason for your answer.
  2. Write down the value of z. Give a reason for your answer.
  3. Work out the value of y. Give a reason for your answer.
62°xyzABCDPQDiagram NOT accurately drawn
3 marks
Show answer
a) x = 62 (corresponding angles are equal) b) z = 62 (alternate angles are equal) c) y = 118 (angles on a straight line add up to 180°)
5

AB and CD are parallel straight lines.

A straight line crosses AB at E and crosses CD at F. On line AB, A is to the left of E and B is to the right of E. On line CD, C is to the left of F and D is to the right of F.

Angle AEF = 62°.

Work out the size of angle CFE.

Give a reason for each stage of your working.

62°ABCDEFDiagram NOT accurately drawn
4 marks
Show answer
118°
6

PQR is a triangle. The side PQ is extended to the point S.

Angle RQS = 112° and angle QPR = 44°.

Show that triangle PQR is isosceles. Give a reason for each stage of your working.

PQR112°44°SDiagram NOT accurately drawn
4 marks
Show answer
Angle PQR = 68 (straight line), angle PRQ = 180 - 44 - 68 = 68 (angles in a triangle), so two angles are equal and the triangle is isosceles.
7

ABC is a triangle. The side BC is extended to the point D.

Angle BAC = a and angle ABC = b.

Prove that angle ACD = a + b.

Give a reason for each stage of your working.

ABabDCDiagram NOT accurately drawn
3 marks
Show answer
Angle ACB = 180 - a - b (angles in a triangle add up to 180°), so angle ACD = 180 - (180 - a - b) = a + b (angles on a straight line add up to 180°)
8
  1. Work out the size of each exterior angle and each interior angle of a regular octagon.
  2. Regular hexagons fit together with no gaps. Regular pentagons do not. Use angles to explain why.
4 marks
Show answer
a) exterior 45°, interior 135° b) Hexagon: 120° × 3 = 360°, so three fit round a point. Pentagon: 108°, and 360 is not a multiple of 108, so there is a gap
9

ABCDEF is a hexagon.

Angle A = angle D = 90°.

The other four interior angles are all equal.

Work out the size of angle B.

4 marks
Show answer
135°
10

AB and CD are parallel straight lines. A straight line crosses them both.

Two co-interior angles between the parallel lines are (3x + 20)° and (2x − 15)°.

Work out the size of the smaller of these two angles.

You must show all your working.

5 marks
Show answer
55°
11

In triangle ABC, AB = AC.

The point D lies on BC so that AD bisects angle BAC.

Prove that triangle ABD is congruent to triangle ACD.

ABCDDiagram NOT accurately drawn
3 marks
Show answer
Triangle ABD is congruent to triangle ACD by SAS
12

AB and CD are parallel straight lines, with AB above CD.

E lies on AB and G lies on CD. F is a point between the two lines, to the right of both E and G, so that EFG forms a zigzag.

Angle BEF = 38° and angle DGF = 44°, where B is to the right of E and D is to the right of G.

Work out the size of angle EFG.

Give a reason for each stage of your working.

38°44°xABCDEFGDiagram NOT accurately drawn
5 marks
Show answer
82°

Extension questions: beyond the core Year 9 objectives, for pupils who want a stretch.

13

ABCDEF is a regular hexagon. ABGH is a square.

The hexagon and the square have the same side length and share the side AB.

F is joined to H.

  1. Work out the size of angle FAH.
  2. Work out the size of angle AFH.

Give a reason for each stage of your working.

ABCDEFGHDiagram NOT accurately drawn
5 marks
Show answer
a) 150° b) 15°

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Every question here is original and written by Robinson Tuition. It follows the Key Stage 3 programme of study; Year 9 sheets end with extension questions for top sets.

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